2016
CHEMISTRY
Paper 2
MARKING SCHEME
FOR EXAMINER’S USE ONLY
MARKING GUIDELINES
SIJIL PENDIDIKAN MRSM EXAMINATION 2016 PAPER 2
Symbol Meaning
// - replace the whole sentence ( ) - replace the previous word
[ ] - can be summarized from explanation ___ or bold - key word
a.d.p - avoid double penalty
wcr - wrong cancel right
a. - accept
r. - reject
e.c.f - error carry forward
1 (a) (i) Neutron (ii) Arrangement of particles: Closely packed in orderly manner
Movement of particles: Vibrate and rotate in fixed position
1 (ii) P1: Heat loss to the surrounding is exactly balanced
P2: by the heat energy liberated by the particles //Heat release to form a bond // heat release to form an attraction force 2 (a) Mixture of two or more elements with a certain fixed
composition in which the major component is a metal. 1 1 (b) Q : Silicon dioxide // Silica // Silicon(IV) oxide // Quartz
R : Copper (ii) Not easily rust // Chemical resistant // Lighter // Easily bend
// Low cost 1
(d) (i) Fermentation 1
4
(ii) Alcohol 1
(iii) C2H5OH C2H4 + H2O 1
(iv) Porcelain chips// pumice stone// aluminium oxide/ concentrated sulphuric acid
a:formula
1
3 (a)(i) Hydrogen ions // H+// Hydroxonium ion // H3O+ 1 1
P2: Concentration of hydrogen ions in E is lower than F
a: vice versa
1
1 2
(iv) P1. Add magnesium powder [any metals more
electropositive than hydrogen]/ calcium carbonate powder[any metal carbonate] to a test tube containing substance F
P2. Efferverscence // Gas bubbles produced // Colourless gas bubbles
(d) Galvanometer // Voltmeter // Miliammeter// Ammeter //Bulb //
EC meter (Electrical conductivity meter) 1 1
(e)(i) Copper/Cu// Silver/ Ag // Lead/Pb // Tin / Sn 1
2 (ii) The distance between magnesium and metal X [metal in e(i)] is
further in the Electrochemical Series //
Metal X is less electropositive than iron 1
(f)(i) Orange// Lemon// Lime// Pineapple// Tomatoes
a: any suitable fruits 1
3 (ii) P1. Contains electrolyte / acid / H+ ion / ions
P2. Have freely moving ions
#If only P2 stated , awarded 2 marks
1 1
5(a) Hydrogen 1 1 (b) P1. Axis with label and unit
P2. Uniform scale ,smooth curve and size ≥ ½ of graph paper P3. All points transferred corrctly
1
Use [correct volume] of [correct molarity higher than 0.1 mol dm-3] of hydrochloric acid [to obtain the same number of mole]
(e.g. 25 cm3 of 2.0 mol dm-3 of HCl)
1 1
(ii)
[Factor : Temperature]
P1. Kinetic energy of particles is higher in K
P2. Frequency of collision between hydrogen ion and magnesium atom is higher in K
P3. Frequency of effective collision between hydrogen ion and magnesium atom is higher in K
Or [Factor : Catalyst]
P1. Catalyst/copper(II) sulphate provide alternative path with lower activation energy
P2. More colliding particles achieve the lower activation energy
P3. Frequency of effective collision between hydrogen ion and magnesium atom is higher in K
Or [Factor : concentration]
P1. The number of particles per unit volume is higher in K P2. Frequency of collision between hydrogen ion and magnesium atom is higher in K
6 (a) (i) +5 1
3
(ii) P4 / Phosphorus 1
(iii) Oxidation number of phosphorus increases from 0 to +5 1
(b) (i) Blue 1
5 (ii) P1. Copper(II) ion is reduced // gain / receive electron to
form copper atom
P2. The concentration of copper(II) ion decreases
1 1 (iii) P1. Mg/ Al/ Zn / [any metal more electropositive than
copper]
P2. Mg + Cu2+ Mg2+ + Cu (based on the named metal G)
1 1
(c) (i) P1. Zn is (more electropositive) / above iron in Electrochemical Series/ the anode //
Zn has higher tendency to release electron
P2. Zn is corroded// sacrificed/ ionised/ oxidised// loss electron
1 1
3
(ii) Zn Zn2+ + 2e 1
7(a)(i) P1. The electron arrangement of Na = 2.8.1, Cl = 2.8.7. P2. Both atoms have 3 shells occupied with electrons. P3. Na and Cl belongs to Period 3.
P4. The number of valence electrons of Na is 1 so it belongs to Group 1.
P5. The number of valence electrons of Cl is 7 so it belongs to Group 17.
(ii) P1. To achieve the stable octet electron arrangement
P2. Sodium / Na atom donate/release /lose 1 electron to form Na+ ions
P3. Chlorine / Cl atom accept / gain / receive 1 electron to form Cl- ions
P4. Na+ ion and Cl- ion attract each other with strong electrostatic force
P5. forms ionic bond with the formula NaCl
[Diagram]
P6. Correct number of electrons
P7. Label nucleus shown and correct charge
# if P2 and P3 is not complete, infer from the half equation
1
(iii) P1. Melting point for the compound formed /
tetrachloromethane/CCl4 is lower than compound in
(a)(ii) /NaCl
P2. Weak intermoleculer force // Van der Waals force between molecules // Weak attraction force between molecules in the compound formed/ tetrachloromethane / CCl4
P3. Less heat energy needed to overcome the forces P4. The ions of compound in (a)(ii) are held together by strong electrostatic force
P5. More heat energy is needed to overcome the force.
(b) P1. Argon atom has achieved stable octet electron arrangement.
P2. Argon atom does not react with tungsten/ atom does not donate, receive or sharing electron / inert
P3. Oxygen atom can accept electron from tungsten atom / reacts with tungsten
Thickener To thicken food Preservative
To make food last longer //
To slow down / prevent the growth of microorganism
Antioxidant To prevent oxidation of food Flavouring Agent To improve the taste of food //
To restore taste loss Any two correct type of food additive and its function
P1. Take full course / finish all the antibiotic
P2. Analgesic (aspirin/paracetamol) has to be taken after food 1 1
1
(b)(i) P1. Carbon dioxide / CO2
P2. Bubble / flow / channel / pass the gas through lime water
P3. Lime water turns milky / chalky / cloudy
1
P2. Add concentrated sulphuric acid slowly/carefully. P3. A brown ring is formed.
1 1
1 3
(c)(i) P1. Barium chloride / Barium nitrate
P2. Sodium sulphate / Potassium sulphate / Ammonium sulphate
1
1 2
(ii) P1. Filter the mixture and rinse
P2. Dry between two filter papers / using oven
1
(ii) P1. Helium gas consists of tiny and discrete particles P2. The particles// helium atoms move freely and randomly P3. The atoms/particles diffuse / move in between the air / move through the air / through the empty space of the balloon’s wall
P4. From the higher concentration area to a lower concentration area
1 1
1
(c) Procedure :
P1. A crucible and its lid is weighed and its mass is recorded.
P2. Clean [5-10]cm of metal Y by using sand paper. Coiled and placed in the crucible.
P3. The crucible with its lid and content is weighed again and the mass is recorded.
P4. The crucible is heated strongly without its lid.
P5. When metal Y starts to burn, close immediately with its lid
P6. Using a pair of tongs, the lid is lifted at intervals.
P6. When the burning has completed, the lid is removed and the crucible is heated strongly for 2 minutes.
P7. The crucible is allowed to cool to room temperature, weighed again and its mass is recorded
P8. The heating, cooling and weighing process are repeated until a constant mass is obtained a: reasonable value
10 (a)(i) P1. Number of mole of butanol = .
+ 9 + + // 0.05 mol
P2. Heat released = mcθ
= 500 x 4.2 x 60 // 126000 J // 126 kJ P3. 0.05 mol of butanol burnt completely to release 126000 J 1 mol of butanol released J
. P4. [value is correct]
2520 kJ
P5. [Negative sign with correct unit]
∆H = - 2520 kJ mol-1
ecf: P3 & P5
1
1
1
1
1 5
(ii) P1. Some heat is lost to the surrounding//heat is absorbed by the apparatus/ tripod stand/ windshield/copper can
P2. Butanol undergoes incomplete combustion // does not undergo complete combustion
1
1 2
(iii) P1. Butanol//Propanol
P2. Correct structural formula of any isomers P3. Name based on isomer in P2
Sample answer :
Structural formula Name
Propan-1-ol
Propan-2-ol
Butan-1-ol
Butan-2-ol
2-methylpropan-1-ol
2-methylpropan-2-ol
1
1
END OF MARKING SCHEME (b) P1. Named metal V
P2. Measure [25.0 – 50.0] cm3 of [0.1-1.0]mol dm-3 copper(II) sulphate solution
P3. Pour the solution into a plastic/ polystyrene cup P4. Record the initial temperature of the solution
P5. Add quickly excess/ 1 spatula of metal V powder into copper(II) sulphate solution
P6. Stir the mixture
P7. Record the highest/maximum temperature reached P8. Data
Initial temperature of copper (II) sulphate solution = T10C
Highest temperature = T2 0C
P9. Heat given out = 25 x 4.2 (T2– T1) = X J
P10. Number of mole of copper(II) sulphate = �� = Y mol
P11. ∆H = - X/Y
= - Z kJmol-1
1 1 1 1 1 1 1
1 1 1
1 11
Max 10
